Tandem organic solar cells(TOSCs),which integrate multiple organic photovoltaic layers with complementary absorption in series,have spurred much interest because of their advantages in harvesting a greater part of the solar spectrum and more efficient photon utilization than the single-junction organic solar cells.In this contribution,we firstly employed the low-bandgap non-fullerene small molecule,IEICO,as electron acceptor in the rare cell,which clearly extent the absorption response of tandem device beyond 900 nm in the near-infrared region.